The Effect of Delay Duration on Delay Discounting Across Adulthood

Objectives Literature about the relationship between age and delay discounting, or the willingness to wait for delayed rewards, is mixed. We posit that some of this heterogeneity may be attributable to inconsistent delay durations across studies. Here we investigate how delay duration influences discounting across adulthood by systematically varying the duration of the delay between the smaller, sooner and the larger, later option. Methods 288 healthy participants (age range: 25–84 years) completed an online delay discounting task that probed 12 different time delays across 3 discount rates. Discounting was analyzed in 2 statistical models that treated delay duration as either a categorical or a continuous predictor. Results Longer delays were generally associated with decreased discounting. However, this was dependent on both age of the participant and delay duration. Both models revealed that, at short to moderate time delays, older adults discounted less than younger adults. However, at very long delays (5 and 10 years), older adults discounted at similar rates to younger adults. Discussion Results suggest that delay length can moderate the relationship between age and discounting. Using delays longer than those tested here (>10 years) could reveal yet another trend (i.e., a reversal) to those found here. Future research should investigate whether this reversal in discounting exists, why it exists, and where the inflection point lies.